Oil amount detector, refrigeration apparatus and air conditioner

Abstract

An oil holding tank ( 40 ) is communicated to the case ( 10 c ) of the compressor ( 10 ). Part of the refrigerant discharged from the compressor ( 10 ) is introduced into the oil holding tank ( 40 ) so that the lubrication oil (L) is allowed to flow out from the oil holding tank ( 40 ) and the lubrication oil (L) which flows out is allowed to return to the case ( 10 c ). The presence of the lubrication oil (L) is detected from a comparison between the temperature (TK 1 ) of the refrigerant introduced from the compressor ( 10 ) to the oil holding tank ( 40 ) and the temperature (TK 2 ) of the lubrication oil ( 4 ) flowing out from the oil holding tank ( 40 ). On the basis of the result of the detection, it is judged whether or not the amount of the lubrication oil (L) in the case ( 10 c ) is appropriate.

What is claimed is:  
     
       1. An oil amount detector of a compressor having a case filled with a lubrication oil, sucking and compressing refrigerant to discharge the refrigerant from the case; the detector comprising: 
       an oil holding tank communicated to the case;  
       a pressuring pipe for introducing part of the refrigerant discharged from the compressor to the oil holding tank for use in pressurization for allowing oil to flow from the oil holding tank;  
       a return pipe for allowing oil flowing out of the oil holding tank to return to the case of the compressor;  
       a first temperature sensor for detecting a temperature of a refrigerant which is introduced to the oil holding tank;  
       a second temperature sensor for detecting a temperature of oil flowing out from the oil holding tank; and  
       detection means for detecting an oil amount in the case from a contrast between the detected temperature of the first temperature sensor and the detected temperature of the second temperature sensor.  
     
     
       2. The detector according to  claim 1 , further comprising: 
       an oil traveling pipe connected between a predefined appropriate oil surface position of the case and the oil holding tank; and  
       a pressure balance pipe connected between the upper portion than the appropriate oil surface position of the case and the oil holding tank.  
     
     
       3. The detector according to  claim 1 , further comprising: 
       an oil traveling pipe connected between a preset appropriate oil surface position of the case and the oil holding tank;  
       a pressure balance pipe connected between the upper portion than the appropriate oil surface position of the case and the oil holding tank;  
       a check valve provided on the oil traveling pipe to suspend the reverse flow of the oil from the oil holding tank to the case; and  
       a check valve provided on the pressure balance pipe to suspend the flow of the refrigerant into the case from the oil holding tank;  
       a bypass pipe connected from the halfway portion of the pressurizing pipe to the return pipe;  
       a pressure reducer provided on the upstream side from the connection portion of the bypass pipe in the return pipe; and  
       a pressure reducer provided on the bypass pipe.  
     
     
       4. The detector according to  claim 3 , wherein one end of the return pipe is communicated to the oil holding tank while the other end thereof is communicated to the case via part of the pressure balance pipe, a first temperature sensor detects the temperature of the refrigerant flowing through the bypass pipe, and a second temperature sensor detects a temperature of oil flowing through the return pipe. 
     
     
       5. The detector according to  claim 1 , further comprising an open and close valve provided on the pressuring pipe. 
     
     
       6. The detector according to  claim 5 , wherein detection means regularly opens the open and close valve, and conducts the detection when opened. 
     
     
       7. The detector according to  claim 1 , wherein the detection means detects the presence of oil in the oil holding tank from a difference between the detected temperature of the first temperature sensor and the detected temperature of the temperature sensor to detect whether or not the oil amount in the case is appropriate. 
     
     
       8. The detector according to  claim 1 , wherein the detection means detects whether or not the oil amount is appropriate or not on the basis of the change with the lapse of time in a difference between the detected temperature of the first temperature sensor and the detected temperature of the second temperature sensor. 
     
     
       9. The detector according to  claim 1 , wherein the detection means detects the time from the rise of the detected temperature of the first temperature sensor up to the rise of the detected temperature of the second temperature sensor to detect whether or not the oil amount is appropriate from a comparison between the detection time and the predefined set value. 
     
     
       10. The detector according to  claim 1 , wherein the detection means starts time count tn at the time when the change amount ΔTK 1  of the detected temperature of the first temperature sensor is consecutively grasped and the change amount ΔTK 1  becomes equal to a predetermined value β or more, or at the time when the detected temperature TK 1  becomes higher than the initial value TK 1 ( 0 ) of the detected temperature by a predetermined value α or more, and then after that the detection means judges the oil amount in the case is appropriate if the time count tn is equal to the predefined set value tns or more when the change amount ΔTK 2  of the detected temperature of the second temperature sensor is consecutively grasped and the change amount ΔTK 2  becomes equal to the predefined predetermined value ΔT or more, or when the detected temperature TK 1  at the time when the time count tn reaches the predefined set value ts is memorized as TK 1 max so that the change amount from the initial value TK 2 ( 0 ) of the detected temperature TK 2  of the second temperature sensor becomes equal to a difference between the initial value TK 1 ( 0 ) and the TK 1 max; whereas if the value is less than the set value tns, the detection means judges that the oil amount in the case is insufficient. 
     
     
       11. The detector according to  claim 10 , wherein the set value ts, the predetermined value ΔT and the set value tns are variably set by using as a parameter a compression ratio of the refrigerant in the compressor and using as a parameter a difference in pressure between a pressure of the refrigerant discharged from the compressor and a pressure of the refrigerant sucked into the compressor. 
     
     
       12. The detector according to  claim 1 , further comprising: 
       an oil recycling pipe connected between the oil holding tank and the pipe on the side of sucking the refrigerant which is sucked into the compressor; and  
       control means for refueling oil in the oil holding tank to the compressor by conducting and controlling the oil recycling pipe.  
     
     
       13. A refrigeration apparatus comprising: 
       a plurality of compressors having a case filled with lubrication oil, the compressors sucking and compressing refrigerant to discharge the refrigerant from the case;  
       oil holding tanks respectively communicated to the cases of the compressors;  
       pressuring pipes for introducing part of the refrigerant discharged from the compressor into the oil holding tanks for use in pressurization for allowing oil to flow out from the oil holding tank;  
       return pipes for allowing oil flowing out from the oil holding tank to return to the case of the compressors;  
       first temperature sensors for detecting respectively the temperature of the refrigerant which is introduced to the oil holding tank;  
       second temperature sensors for detecting respectively the temperature of the refrigerant which flows out from the oil holding tank;  
       detection means for detecting respectively an oil amount in the case of the compressors from a contrast between the detected temperature of the first temperature sensors and the detected temperature of the second temperature sensors;  
       oil recycling pipes connected between oil holding tanks and pipings on the side of sucking the refrigerant, the pipings allowing the refrigerant to be sucked to the compressors to pass therethrough;  
       an oil balance pipe mutually connected to the oil recycling pipes; and  
       control means for refueling oil in the oil holding tank to the compressors by conducting and controlling the oil recycling pipes.  
     
     
       14. An air conditioner comprising: 
       a plurality of compressors having a case filled with lubrication oil, sucking and compressing refrigerant to discharge the refrigerant from the cases;  
       a plurality of outdoor units provided with the compressors;  
       a plurality of indoor units;  
       a refrigerating cycle constituted of the piping connection of the outdoor units and the indoor units;  
       oil holding tanks respectively connected to the case of the compressors;  
       pressuring pipes for respectively introducing a part of the refrigerant discharged from the compressors for use in pressurization for allowing the oil to flow out from the oil holding tanks;  
       oil recycling pipes respectively connected between the oil outflow port of the oil holding tanks and the piping on the side of sucking the refrigerant, the piping allowing the refrigerant sucked in the compressor to pass therethrough; and  
       oil balance pipes mutually connected between the oil recycling pipes.  
     
     
       15. The air conditioner according to  claim 14 ; further comprising: 
       oil traveling pipes connected between predefined appropriate oil surface position of the case of compressors and the oil holding tanks; and  
       pressure balance pipes connected between the upper portion than the appropriate oil surface position of the case of the compressors and the oil holding tanks.  
     
     
       16. The air conditioner according to  claim 14 , further comprising: 
       detection means for respectively detecting whether the oil amount in the case of the compressors is appropriate or insufficient; and  
       control means for controlling the conduction of the pressuring pipes and the oil recycling pipes so that oil in the oil holding tanks flow to the compressors in which the shortage of the oil amount is detected with the detection means.  
     
     
       17. The air conditioner according to  claim 14 , further comprising: 
       control means for controlling the conduction of the pressuring pipes and the oil recycling pipes so that the oil amount is balanced mutually between the outdoor units.  
     
     
       18. The air conditioner according to  claim 17 , wherein the control means controls the conduction of the pressuring pipes and the oil recycling pipes so that the oil retained in the outdoor units on the side of a low operation ratio is temporarily collected in the outdoor units on the side of a high operation ratio on a regular basis, and the collected oil is allowed to return to the outdoor units on the side of the low operation ratio. 
     
     
       19. The air conditioner according to  claim 14 , further comprising: 
       control means for controlling the conduction of the pressuring pipes and the oil recycling pipes so that oil retained in the suspended outdoor units out of the outdoor units flows to the outdoor units which is operated.  
     
     
       20. An air conditioner comprising: 
       a plurality of outdoor units having a compressor having a case filled with lubrication oil, sucking and compressing refrigerant to discharge the refrigerant from the case, a change-over valve changing over a refrigerant flow in the cooling mode and a refrigerant flow in the heating mode, and an outdoor heat exchanger;  
       a plurality of indoor units having an indoor heat exchanger;  
       a heat pump type refrigerating cycles constituted of the piping connection of the compressors, the change-over valves, the outdoor heat exchangers, and the indoor heat exchangers, the pipes on the liquid side are shared by one pipe and the pipes on the gas side are shared by one pipe;  
       oil traveling pipes respectively connected to the case of the compressors;  
       oil recycling pipes connected from the oil traveling pipes to pipings on the side of sucking the refrigerant, the pipings allowing the refrigerant to be sucked to the compressors to pass therethrough;  
       an oil balance pipe mutually connected between the oil recycling pipes; and  
       control means for setting at least one of the outdoor units to a heating mode while setting the remaining outdoor units to a cooling mode, and at the same time, operating the outdoor units set to the heating mode while suspending the outdoor units set to the cooling mode.  
     
     
       21. The air conditioner according to  claim 20 , wherein detection means is provided for detecting whether or not the oil amount in the case is appropriate or insufficient. 
     
     
       22. The air conditioner according to  claim 21 , wherein the control means sets to the heating mode the outdoor units having the compressors in which the oil amount is insufficient in the case where the detection means detects the shortage of oil amount. 
     
     
       23. The air conditioner according to  claim 20 , wherein the control means regularly conducts control. 
     
     
       24. The air conditioner according to  claim 20 , wherein the oil traveling pipes are connected to the appropriate oil surface position of the cases. 
     
     
       25. The air conditioner according to  claim 20 , further comprising the oil holding tanks respectively provided between the connection between the oil traveling pipes and the oil recycling pipes. 
     
     
       26. An air conditioner comprising: 
       a plurality of outdoor units having a compressor having a case filled with lubrication oil, sucking and compressing refrigerant to discharge the refrigerant from the case, a change-over valve changing over a refrigerant flow in the cooling mode, a refrigerant flow in the heating mode and a refrigerant flow in the defrosting mode and an outdoor heat exchanger;  
       a plurality of indoor units having an indoor heat exchanger;  
       a heat pump type refrigerating cycles constituted of the piping connection of the compressors, the change-over valves, the outdoor heat exchangers, and the indoor heat exchangers, the pipes on the liquid side are shared by one pipe and the pipes on the gas side are shared by one pipe;  
       oil traveling pipes respectively connected to the case of the compressors;  
       oil recycling pipes connected from the oil traveling pipes to pipings on the side of sucking the refrigerant, the pipings allowing the refrigerant to be sucked to the compressors to pass therethrough;  
       an oil balance pipe mutually connected between the oil recycling pipes;  
       control means for changing over the outdoor units to the defrosting mode on a regular basis or when needed in the case where the outdoor units are set to the heating mode to conduct a defrosting operation with respect to the outdoor heat exchanger; and  
       control means for delaying the defrosting mode from the heating mode in at least one of the outdoor units at the time of the start of the defrosting operation, and operating the outdoor unit which is to be delayed while suspending the operation of the remaining outdoor units in the defrosting mode.  
     
     
       27. The air conditioner according to  claim 26 , wherein the oil traveling pipes are connected to the appropriate oil surface position of the cases. 
     
     
       28. The air conditioner according to  claim 26 , further comprising oil holding tanks respectively provided between the connection between the oil traveling pipes and the oil recycling pipes.